Wireless signaling



March 13, 1928. 1,662,459

c. s. FRANKLIN ET AL WIRELESS SIGNALING Filed May 17. 1922 Imp/MW 7b Willa/or anmmtoz GSIRANKUN a r gg ifiena q y en ECKERSLEY Patented Mar. 13, 1928.

UNITED STATES PATENT OFFICE.

CHARLES SAMUEL FRANKLIN, F BUCKHUBST HILL, AND PETER PENDLETON ECK- ERSLEY, OF WITHAIII, ENGLAND, ASSIGNORS TO RADIO GORPORATIONOF A CORPORATION or DELAWARE.

AMERICA,

WIRELESS SIGNALING.

Application filed May 17, 1922, Serial No. 561,558, and in Great Britain May 25, 1921.

According to our invention we construct an aerial system which has a common part and two branches connected to and prefen ably connecting this common part to earth, the time period of the first branch being equal or approximately so to that of the common part, while the second branch has a different time period, in other words the second branch is connected to the combination of the common part and the first branch at or near to a node of potential, so that the introduction of this second branch will not aflect the tune of the combination of the common part and the first branch. To this combination we couple a circuit in which oscillations can be generated for transmission. This will result in relatively small currents of the transmitted wave length flowing in the second branch. If therefore,

waves of a length corresponding to the tune of the combination of the common part and the second branch be emitted from a distant station, such Waves falling upon the system will cause beat currents to be set up in the second branch. To this second branch therefore we couple a circuit in which the beat currents can be rectified and passed to a circuit tuned to the beat frequency which may be Widely different from that of the transmitted frequency, so that any oscillationswhich may be set up in this last men tioned circuit fron'i the local transmitter will very feeble and will not affect the reception of signals from the distant station.

Our invention illustrated by the accom panying diagram.

The aerial system hasa commonpart Lo and two branches containingcapacities and inductances L25, Gt, and L1, Gr. e adjust the value of Lt, Ct, soflthat the branch Lt, Ct, is in resonance with the common part. Thus when currents of the frequency Nt, to which the common part and the branch Lt, Ct, are tuned; are induced into the aerial A by a circuit T, the point 0 becomes nearly a n d e of potential and nearly all such currents flow in the path Lt, Ct. Thus we make e erial y t m t L Lt, C our transmitting radiation system and comparatively large currents are caused to-flow therein.

By suitably choosing the values of Lr, Cr,

the aerial system is given another period tuned to the wave length to be'received and a large part of the received currents is confined to the path L7, C1.

Owing, however, to the resistance of the path Lt, Ct, some of the currents of the tcransmitted frequency Nt, will flow in L1",

he intensity of the currents set up in the. aerial L0, Lt, Ct, is very great compared to the received oscillations, but the intensity of the currents that leak into the path L1", Or, are, due to the point 0 being nearly nodal to the frequency Nt, commensurate with the received oscillations.

Thus in the pathLr, Cr, there are set up two commensurate oscillations of frequency Ni, and N1, the latter being the frequency of the received Waves. i i

These oscillations beat together .and produce in the close coupled circuit L C, which is tuned to the frequency N7, a frequency Nb i NH N1. By rectifying these beats suitably by a three electrode valve .V or other rectifying device, a circuit Lb, CZ) tuned to a frequency Nb can be set into oscillation.

An amplifier can then be associated with Lb, CI), to amplify these beats and manifcst- 1y can be arranged to amplify at a frequency far removed from that of the powerful transmitting currents. and. can therefore functioneificiently without interference from such currents.

The most difiicult problem is to prevent the oscillatory currents of frequency N2 which leak into L7, C1, from being too powerful and so swamping the valve V.

The inductance Lt. must therefore be made of a. resistance as low as possible. o

In some cases we may arrange for a nega tive potential to be established between the grid and filament of the valve V by means of potentiometer P. a

\Ve have found it advisable to use coupled rect wipe out of the amplifier due to the curren s of freq ency} fiowiugin L1", Cr-

We have found it advantageous sometimes to arrange ni'utualcQHPhngs between the two paths Lo", Cr, and L5, 025, so as to'balance circuits at Lb, CZ), inorder to prevent-diof transmitted curbranch In, (12'. invention, what we out too great a leakage rents into the receiving Having described our claim is:

1. In signaling systems, a transmitting-recciving circuit comprising a common portion and a pair of mutually coupled branches connected to said common portion, said common portion and one of said branches being adjusted to be resonantly responsive to oscillations of a predetermined frequency. and said common portion and the other branch being adjusted to be resonantly responsive to oscillations of a. different frequency, and a circuit coupled to one of said braiiches and comprising a portion resonantly responsive to oscillations of a tretpiency equal to the difference between said first two fretpiencies.

Q. In signaling syste is, a transmitting-receiving circuit comprising a counnon portion and a pair of mutually coupled branches connected to said common portion, said common portion and one of said branches being adjusted to he resonantly responsive to oscillations of a predetermined frequency. and said common portion and said other branch being adjusted to be resonantly responsive to oscillations of a different frequency, means for generating in said common portion and one of said branches oscillations of the frequency to which said common portion and said branch are responsive, and a circuit coupled to the other of said branches and comprising a portion resonantly responsive to oscillations of a frequency equal to the difference between said first two frequeneies.

3. In signaling systems, a transmitting-receiving circuit comprising a common portion and a pair of mutually coupled branches connected to said common portion, said common portion and one of said branches being adjusted to be resonantly responsive to oscillations of a, predetermined frequency, and said connnon portion and said other branch being adjusted to be resonantly responsive to oscillations of a different frequency, means for generating in said connnon portion and one of said bra'nehes oscillations of. the frequency to which said common portion and said branch are responsive. and a circuit coupled to the other of said branches and comprising coupling means and a portion resonantly responsive to oscillations of a frequency equal to the difference between said first two frequencies, and a rectifier interposed between said coupling means and said last named portion.

4. In signaling systems, a transmitting-receiving circuit comprising a common portion anda pair of mutually coupled'branches connected to said common portion, said'common portion and one of said branches being adjusted to be resonant-1y responsive to oscillatioris of a predetermined frequency, and

said common portion and said other bran h being adjusted to be resonantly responsive to oscillations of a different frequemry, means for generating in said common portion and one of said branches oscillations one of said branches being tuned to a predetermined frequency, said common portion and the other of said branches being tuned to a predetermined different frequency, means for supplying to one of said branches oscillations of a frequency adapted to beat with oscillations of the frequency to which said branch is tuned, an additional circuit coupled to said branch and comprising a detector and means for selectively an'iplifying oscillations of beat frequency.

6. In a signaling system, a transmittingrcceiving circuit comprising a common portion and a pair of mutually coupled branches connected to said common portion, said common portion and one of said branches being tuned to a predetermined frequency, said common portion and said other branch being tuned to a predetermined different frequency, means associated with one of said branches for producing, in said branch oscillations of a frequency to which said branch is tuned, a circuit coupled to the other of said branches and cmnprising a detector and means for selectively an'iplifying oscillations of a frequency equal to the difference between the first; two named frequencies.

7 1p a signaling svstein, a transn'iittingreceiving circuit comprising a common portion and a pair of branches conne t d to said common portion, said common portion and one of said branches being tuned to a predetermined frequcncy, said common portion and said other 1. 'anch being tuned to a pre determined different frequency, means associated with one of said branches for pro ducing in said branch oscillations of a frequency to which said b much is tuned, a circuit coupled to the other of said branches and comprising, a detector and means for selectively amplifying oscillations of a frequency equal to the difference between the first two frequencies, and means for varying the coupling between said branches independently of variations in tuning.

8. In a signaling system, a transmittingltll) receiving circuit comprising a common portion and a pair of branches connected to said common portion, said common portion and one of said branches being tuned to a predetermined frequency, said common portion and said other branch being tuned to a predetermined different frequency, means associated with one of said branches for producing in said branch oscillations of the frequency to which said branch is tuned, a circuit'coupled to the other of said branches and comprising a detector and means for selectively amplifying oscillations of a frequency equal to the difference between the first two frequencies, and means independ ent of tuning for controlling the amount of current of the first mentioned frequency flowing in said last mentioned branch.

9. In a signaling system, a transmittingrcceiving circuit comprising a common portion and a pair of branches connected to said common portion, said common portion and one of,said branches being tuned to a predetermined frequency, said common portion and said other branch being tuned to a predetermined different frequency, means associated with one of said branches for pro ducing in said branch signaling oscillations of the frequency to which said branch is tuned, a receiving circuit coupled to the other of said branches and comprising a detector, and means for selectively amplifying oscillations of a frequency equal to the difference between the first two frequencies, and means for permitting a predetermined amount of oscillatory current of signaling frequency to flow in the second branch to produce beats With oscillatory currents vof the frequency to which said branch is tuned.

CHARLES SAMUEL FRANKLEN. PETER PENDLETON ECKERSLEY. 

